Methods for reducing the viscosity of treatment fluids comprising diutan

Abstract

Methods are provided that include a method comprising providing a treatment fluid comprising a base fluid and a gelling agent that comprises a diutan composition; providing a breaker that comprises an acid composition; allowing the breaker to interact with the treatment fluid; and allowing the viscosity of the treatment fluid to decrease. In some embodiments, the treatment fluid may comprise a base fluid, a gelling agent that comprises a diutan composition, and a breaker that comprises an acid composition. In some embodiments, the treatment fluid may be introduced into a portion of the subterranean formation at or above a pressure sufficient to create or enhance one or more fractures in the portion of the subterranean formation. Additional methods are also provided.

1. A method comprising:
 providing a treatment fluid comprising a base fluid and a gelling agent that comprises a clarified diutan composition that has a transmittance at 600 nm wavelength of at least about 65% in a 1 centimeter optical cell, at 0.1% concentration in deionized water, wherein the treatment fluid is not foamed, and wherein the gelling agent does not comprise clarified xanthan; 
 providing a breaker that comprises an acid composition; 
 contacting the treatment fluid with the breaker; 
 allowing the breaker to interact with the treatment fluid; and 
 allowing the viscosity of the treatment fluid to decrease. 
 
     
     
       2. The method of  claim 1  wherein the acid composition is selected from the group consisting of: an acid, an acid generating compound, and combinations thereof. 
     
     
       3. The method of  claim 1  wherein the acid composition comprises an acid selected from the group consisting of: formic acid, acetic acid, carbonic acid, citric acid, glycolic acid, lactic acid, ethylenediaminetetraacetic acid, hydroxyethyl ethylenediamine triacetic acid, hydrochloric acid, hydrofluoric acid, p-toluenesulfonic acid, and combinations thereof. 
     
     
       4. The method of  claim 1  wherein the acid composition comprises an acid generating compound selected from the group consisting of: esters, aliphatic polyesters, ortho esters, poly(ortho esters), poly(lactides), poly(glycolides), poly(ε-caprolactones), poly(hydroxybutyrates), poly(anhydrides), ethylene glycol monoformate, ethylene glycol diformate, diethylene glycol diformate, glyceryl monoformate, glyceryl diformate, glyceryl triformate, triethylene glycol diformate and formate esters of pentaerythritol, copolymers thereof, derivatives thereof, and combinations thereof. 
     
     
       5. The method of  claim 1  wherein the breaker further comprises a pH-adjuster. 
     
     
       6. The method of  claim 5  wherein the pH-adjuster is selected from the group consisting of: sodium formate, potassium formate, sodium acetate, potassium acetate, sodium citrate, potassium citrate, sodium glycolate, potassium glycolate, sodium maleate, potassium maleate, sodium phosphate, potassium phosphate, potassium dihydrogen phosphate, cesium formate, combinations thereof, and derivatives thereof. 
     
     
       7. The method of  claim 5  wherein the pH-adjuster is present in an amount sufficient to maintain or adjust the pH of the fluid to a pH in the range of from about 1 to about 5. 
     
     
       8. A method comprising:
 providing a treatment fluid, wherein the treatment fluid is not foamed and comprises:
 a base fluid, 
 a gelling agent that comprises a clarified diutan composition that has a transmittance at 600 nm wavelength of at least about 65% in a 1 centimeter optical cell, at 0.1% concentration in deionized water, wherein the gelling agent does not comprise clarified xanthan, and 
 a breaker that comprises an acid composition; 
 
 introducing the treatment fluid into at least a portion of the subterranean formation; and 
 allowing the viscosity of the treatment fluid to decrease through an interaction of the breaker with the gelling agent. 
 
     
     
       9. The method of  claim 8  wherein the gelling agent is present in the treatment fluid in an amount in the range of from about 0.25 lbs/Mgal to about 200 lbs/Mgal. 
     
     
       10. The method of  claim 8  wherein the acid composition is selected from the group consisting of: an acid, an acid generating compound, and combinations thereof. 
     
     
       11. The method of  claim 8  wherein the acid composition comprises an acid selected from the group consisting of: formic acid, acetic acid, carbonic acid, citric acid, glycolic acid, lactic acid, ethylenediaminetetraacetic acid, hydroxyethyl ethylenediamine triacetic acid, hydrochloric acid, hydrofluoric acid, p-toluenesulfonic acid, and combinations thereof. 
     
     
       12. The method of  claim 8  wherein the acid composition comprises an acid generating compound selected from the group consisting of: esters, aliphatic polyesters, ortho esters, poly(ortho esters), poly(lactides), poly(glycolides), poly(ε-caprolactones), poly(hydroxybutyrates), poly(anhydrides), ethylene glycol monoformate, ethylene glycol diformate, diethylene glycol diformate, glyceryl monoformate, glyceryl diformate, glyceryl triformate, triethylene glycol diformate and formate esters of pentaerythritol, copolymers thereof, derivatives thereof, and combinations thereof. 
     
     
       13. The method of  claim 8  wherein the treatment fluid further comprises a pH-adjuster selected from the group consisting of: sodium formate, potassium formate, sodium acetate, potassium acetate, sodium citrate, potassium citrate, sodium glycolate, potassium glycolate, sodium maleate, potassium maleate, sodium phosphate, potassium phosphate, potassium dihydrogen phosphate, cesium formate, combinations thereof, and derivatives thereof. 
     
     
       14. A method of stimulating a portion of a subterranean formation comprising:
 providing a treatment fluid that comprises a base fluid and a gelling agent that comprises a clarified diutan composition that has a transmittance at 600 nm wavelength of at least about 65% in a 1 centimeter optical cell, at 0.1% concentration in deionized water, wherein the treatment fluid is not foamed, and wherein the gelling agent does not comprise clarified xanthan; 
 providing a breaker that comprises an acid composition; 
 introducing the treatment fluid into a portion of the subterranean formation at or above a pressure sufficient to create or enhance one or more fractures in the portion of the subterranean formation; 
 allowing the breaker to interact with the treatment fluid; and 
 allowing the viscosity of the treatment fluid to decrease. 
 
     
     
       15. The method of  claim 14  wherein the acid composition is selected from the group consisting of: an acid, an acid generating compound, and combinations thereof. 
     
     
       16. The method of  claim 14  wherein the treatment fluid further comprises a pH-adjuster selected from the group consisting of: sodium formate, potassium formate, sodium acetate, potassium acetate, sodium citrate, potassium citrate, sodium glycolate, potassium glycolate, sodium maleate, potassium maleate, sodium phosphate, potassium phosphate, potassium dihydrogen phosphate, cesium formate, combinations thereof, and derivatives thereof.